A present invention is related to a forward/backward switch protective structure for a remotely controllable car. When a throw plates of the output shaft are outward centrifugally extended, a shade body is located and prevented from moving. Therefore, respective components are protected from being impacted and worn out due to instantaneous switching between forward and backward rotation.
FIGS. 7 and 8 show a forward/backward power coupler of a remotely controllable car. A forward gear 82 and a backward gear 83 are disposed on an output shaft 81. The forward and backward gears 82, 83 are driven by a gear set 85 driven the same engine 84. In addition, the forward and backward gears 82, 83 are respectively provided with clutch seats 821, 831. The clutch seats 821, 831 respectively have clutch plates 822, 832. The output shaft 81 has a differential section 811 between the forward and backward gears 82, 83. A clutch shade 86 is fitted on the differential section 811. The clutch shade 86 has a differential hole 860 through which the differential section 811 is fitted. The clutch shade 86 is formed with annular grooves 861, 862 respectively corresponding to the clutch plates 822, 832 of the forward and backward gears 82, 83. When outward extended, the clutch plates 822, 832 are inserted into the annular grooves 861, 862 for driving the clutch shade 86 to drive the output shaft 81.
In addition, the clutch shade 86 has an annular groove 863 in which a shifting plate 87 is inlaid. A servo (not shown) drives the shifting plate 87 to push the clutch shade 86.
In a state that the clutch shade 86 covers the clutch seat 821 of the forward gear 82 as shown in FIG. 7, when the engine 84 drives the gear set 85 to rotate the forward gear 82, the clutch plate 822 in the clutch seat 821 will centrifugally extend outward to abut against inner edge of the annular groove 861 of the clutch shade 86 to further drive the clutch shade 86 for driving the output shaft 81, making the remotely controllable car move forward.
When the rotational speed of the engine 84 is reduced and the rotational speed of the forward gear 82 is slowed down, the spring 823 in the clutch seat 821 will push the clutch plate 822 and restore the clutch plate 822 into the clutch seat 821 without contacting with the clutch shade 86 as shown in FIG. 8. At this time, the servo can drive the shifting plate 87 to push the clutch shade 86 to a position where the clutch shade 86 covers the clutch seat 831 of the backward gear 83. Then, when the backward gear 83 is such rotated that the clutch plate 832 extends outward to contact with the annular groove 862 of the clutch shade 86, the clutch shade 86 is driven in reverse direction to backward drive the output shaft 81, whereby the remotely controllable car is moved backward.
However, when the clutch plate 822 is restored into the clutch seat 821 without contacting with the clutch shade 86, the clutch shade 86 and the output shaft 81 are still in a not driven and freely rotatable state. Therefore, the remotely controllable car will inertially move forward. In other words, when the clutch shade 86 is pushed by the shifting plate 87 to the position where the clutch shade 86 covers the clutch seat 831 of the backward gear 83, the clutch shade 86 and the output shaft 81 still inertially rotate forward. However, the engine 84 is able to instantaneously stop operating and then operate to a high speed state. At this time, the backward gear 83 is driven to make the clutch plate 832 extend outward. When the clutch plate 832 of the backward gear 83 contacts with the annular groove 862 of the still forward rotating clutch shade 86, the backward rotating clutch plate 832 will suffer a very great friction in reverse direction. Accordingly, the clutch plate 832 is easy to be quickly worn out and the backward gear 83 and the gear set 85 will bear considerably great reaction force. Similarly, when the clutch shade 86 is switched from backward state to forward state, the above abnormal wear and reaction force will also take place. As a result, the clutch plates 822, 832 and the gear set 85 will be quickly worn out to shorten the using life of the transmission mechanism.
Furthermore, the output power of the engine 84 is transmitted by the gear set 85 to the clutch plate 822 or 832 and then by means of the frictional contact between the clutch plate and the clutch shade 86, the clutch shade 86 drives the output shaft 81 to rotate. The frictional loss between the two clutch plates 822, 832 and the clutch shade 86 will lead to declination of the output power of the engine 84. Therefore, the power can be hardly truly transmitted. This seriously affects the performance of the remotely controllable car, especially in a race.
There is no design for reducing friction between the clutch shade 86 and the shifting plate 87. In other words, the quicker the rotational speed of the clutch shade 86 is, the greater the frictional loss between the shifting plate 87 and the clutch shade 86 is. This increases unnecessary power loss.
It is therefore a primary object of the present invention to provide a forward/backward switch protective structure for remotely controllable car. Two throw plates are pivotally disposed in a seat body fixed on the output shaft. When the output shaft rotates, the throw plats are outward centrifugally extended and inserted into the annular grooves of a shade body to prevent the shade body from moving and avoid switch between forward and backward rotation. Therefore, the respectively transmission components are protected.
It is a further object of the present invention to provide the above forward/backward switch protective structure in which the differential section of the output shaft is fitted in the corresponding differential engaging hole of the shade body and the engaging sections of the shade body are respectively engaged with the stop sections of the forward and backward gears. Therefore, the power can be truly and directly transmitted from the forward and backward gears via the shade body to the output shaft.
It is still a further object of the present invention to provide the above forward/backward switch protective structure in which the arched insertion member of the shifting mechanism is located by both the link and the insertion rod. Therefore, when inserted into the rail of the shade body, the insertion member will not deflect to contact with the shade body. Accordingly, when the output shaft rotates, the friction between the shade body and the insertion member is avoided.